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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        const cartList = [
            { goods_id: 11, goods_name: '商品1' },
            { goods_id: 22, goods_name: '商品2' },
            { goods_id: 33, goods_name: '商品3' },
            { goods_id: 44, goods_name: '商品4' },
            { goods_id: 55, goods_name: '商品5' },
        ]

        const goods_id = 33;
        // findIndex()  查找索引
        // 查找成功：返回数组索引（找到后会自动停止查找）。
        // 查找失败：返回 -1

        //find()   查找数组项
        //    查找成功：返回数组项
        //    查找失败：返回 undefined  
        const index = cartList.findIndex((item) => item.goods_id === goods_id)
        const obj = cartList.find((item) => item.goods_id === goods_id)
        console.log('cartList', cartList);
        console.log(`goods_id为${goods_id}的索引值是:${index}`)
        console.log('find查找数组项',obj);


    // const goods_id = 22;
    // let index = 0;
    // for (let i = 0; i < cartList.length; i++) {
    //   const item = cartList[i]
    //   if (item.goods_id === goods_id) {
    //     index = i;
    //     break;
    //   }
    // }
    // console.log(index);
    </script>
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